en:docs:dos:api:int21:53

Note: This API call is for DOS personality only. Use Family API for portability.

2018/09/07 07:04 · prokushev

Int 21H, AH=53H

Version

2 and higher

Brief

TRANSLATE BIOS PARAMETER BLOCK TO DRIVE PARAM BLOCK

Family API

Input

AH = 53h
DS:SI -> BIOS Parameter Block (see #01663)
ES:BP -> buffer for Drive Parameter Block (see #01395 at AH=32h)
    DBP drive byte must be set to valid drive (Windows95-OSR2)
---Windows95---
CX = signature 4558h ('EX') for FAT32 extended BPB/DPB (see #01664)
DX = signature 4152h ('AR') for FAT32 extended BPB/DPB

Return

 ES:BP buffer filled

Notes

for DOS 3.0+, the cluster at which to start searching is set to 0000h
  and the number of free clusters is set to FFFFh (unknown)
if the number of sectors per cluster is set to zero, MS-DOS will hang
  at startup because it computes the internally-used shift count by
  shifting this value right until the carry flag is set; since this
  will never happen when the field is zero, MS-DOS hangs
not supported by Windows NT 3.1
        

See also

Note


en/docs/dos/api/int21/53.txt · Last modified: 2021/05/02 07:42 by prokushev